Plants of the Epimedium genus belonging to the Berberidaceae family are classified into three species of E. brevicornum, E. sagittatum and E. koreanum, as described in Chinese pharmacopoeia. It has been reported that the plants of the Epimedium genus comprise main components of flavonoid, alkaloid and lignan. Particularly, the herb medicine prepared by drying the whole plant except for the root of Epimedium koreanum Nakai is called Epimeii Herb and has been used for treatment of total paralysis and amnesia, and an aphrodisiac and analeptic agent.
It is known that oxygen free radical generated by various physical, chemical and environmental factors such as enzyme system and reductive metabolism in the body, chemicals, pollutants and photochemical reaction induces various diseases including cell aging or cancers by non-selective, irreversible destruction against lipid, cell constituting materials such as protein, sugar and DNA. Also, the oxygen free radical is a cause of many diseases since various peroxides in the body including lipid peroxides generated by peroxidization of lipid by the oxygen free radical bring about oxidative destruction of cells, leading various functional disorders.
Therefore, anti-oxidants such as free radical scavengers capable of removing free radical or substances inhibiting formation of peroxides such free radical are expected to be inhibitants or therapeutic agents against aging and various diseases caused by these peroxides.
For development of natural anti-oxidants, many materials derived from natural sources were studied. However, most of the materials derived from natural sources were used in a simple extract form and substances, to which the effect of the extract was attributed, were not clearly shown. The materials have been used in the cosmetic composition by experience and information by word of mouth.
Meanwhile, the skin aging is largely classified according to its cause. One is natural aging (Intrinsic aging), in which the structure and physiological functions of the skin are continuously degraded as one becomes older. The other one, that is extrinsic aging is caused by external stress accumulated such as solar rays. Particularly, ultraviolet rays (UV) among the sun beams are the main cause of aging. When the skin is exposed to UV rays for a long period of time, the stratum corneum is thickened and collagen and elastin are denatured, whereby the skin loses its elasticity. These collagen and elastin are controlled by many factors. By the expression of matrix metallo protease such as collagenase and elastase, the synthesized collagen and elastin are decomposed and consequently, the collagen level in the skin is reduced.
In order to inhibit decrease of collagen and elastin which are causes of reduction of elasticity, many substances have been developed and used. Among them, retinoids such as retinol and retinoic acid show improvement of elasticity (Dermatology therapy, 1998, 16, 357 to 364) and a protein fraction obtained from Leguminosae seeds showed increase in elasticity (U.S. Pat. No. 5,322,839).
However, these retinoids have defects that they may cause irritation when they are applied on the skin even in a small amount. They are mainly materials derived from natural materials and thus, it is not clarified that which components of the extract show the effect. Accordingly, it is difficult to maintain and control the activity of the extract.
Meanwhile, many factors participate in determination of the skin color of human bodies. Particularly, activity of melanocyte, where melanin pigment is formed, distribution of blood vessels, skin thickeness and presence of a pigment such as carotenoid and bilirubin in the outside or inside of the body are important.
The most important factor among them is melanin, a black pigment, produced by action of various enzymes such as tyrosinase in melanocyte of the human body. The formation of this melanin pigment is affected by genetic factors, physiological factors associated with hormone secretion and stress and environmental factors such as irradiation of UV rays.
The melanin pigment generated in melanin cells of the human skin is a high-molecular weight phenolic compound having a composite structure of a black pigment and a protein and intercepts UV rays from the sun to protect skin organisms under the dermis while protecting proteins and genes in the skin by capturing free radicals produced in the skin.
As described above, melanin generated by the external stress stimulation is a stable substance which does not disappear, even when the stress is released, until it is discharged through keratinization of the skin. However, when melanin is generated excessively over the needed amount, hyper-pigmentation, cosmetically undesirable conditions, such as discoloration, freckles or speckles may be induced.
Also, as the number of people who enjoy the outer activities is increased due to the increase of leisure population, there is a need to prevent pigmentation of melanin by UV rays.
In order to satisfy the above-described need, ascorbic acid, kojic acid, arbutin, hydroquinone, glutathion or derivatives thereof, or substances having inhibition activity on tyrosinase have been used in cosmetic compositions of pharmaceutical products. However, the use of these substances is limited because of insufficient whitening effect, safety upon use on the skin, formulation and safety problems occurring when added to cosmetic compositions.